1. Field of the Invention
The present invention relates to an apparatus and a method thereof for applying a coating solution on a continuous base (hereinafter web) with a solution in slide bead method for producing photographic film, photographic paper, photosensitive printing material, medical photosensitive material, micro film, magnetic recording tape, adhesive tape, pressure sensitive recording paper, thermosensitive recording paper, off-set printing material, film for liquid crystal display, and the like.
2. Description Related to the Prior Art
In a coating apparatus for applying a coating solution on a web in a slide bead method, a method for regulating a form of edges of the coating solution are disclosed in Japanese Patent Laid-Open Publications No. 55-84577, 10-128212, 10-151397, 10-165870, and 10-165872. In the method disclosed in the publications, a thickness of a coating layer at the edge is regularized by forming the best shape of an edge plate for regularizing a width of the solution on a slide surface, by blowing an air blow to the edge, and inserting a slot to the edges and the like.
However, the above mentioned coating apparatus has complex structure for which fine adjustments are necessary. When the coating apparatus is renewed, a difference of accuracy between the coating apparatuses causes to prevent from being in the best condition.
A method for solving the problem is disclosed in Japanese Patent No. 3-71185 and Japanese Patent Laid-Open Publication 7-502685. However, the coating apparatus described in the former publication often causes a defect of the edges of bead. Further an operation of the coating apparatus described in the latter publication is not so easy as to make a positional adjustment of an edge plate with a hopper edge guide device, and the determination of position of the edge plate is hard.
Further as shown in FIG. 21, when a height Dg of a side perpendicular wall 101 of an edge plate 100 is made to be less than the minimum thickness Db of bead of a coating solution, a flow of the solution 117 cannot be regulated only by the side perpendicular wall 101 at a minimum thickness position Dr of bead. Accordingly, a vena contracta is generated at the minimum thickness position Dr of the bead, the thickness at the edges of the coating solution becomes large, which causes the defect in drying.